Patent GB-650513-A (GB)
Title: Improvements in and relating to control systems for aircraft
IPC: G05D1/00
Filed: 1946-05-15
Abstract: 650,513. Controlling aircraft. SPERRY GYROSCOPE CO., Inc. May 15, 1946, No. 14720. Convention date, May 15, 1945. [Class 4] [Also in Groups XXIX and XXXV] In an aircraft having an automatic pilot controlling the surfaces determining bank, pitch and yaw, a further automatic control system is provided enabling the craft to be recovered to straight level flight even if it should be upside down or have lost its proper sustaining airspeed. In Fig. 1 a direction gyroscope 2 carrying a coil 6 of a Selsyn generator 3 controls the rudder R through a phasesensitive rectifier 7 and servomotor 8, rotation of knob 10 changing the course. A stabilizing gyro 13 similarly controls the elevator E and ailerons A by servomotors 20, 22 and the respective signal coils 16<SP>1</SP>, 17<SP>1</SP> are rotated on shafts 181, 19<SP>1</SP> by knobs 18, 19 to effect pitch and roll of the aircraft respectively. By pressing the master control button 24, a bar 26 moves back against springs 30 causing arms 31 to disengage serrations on the sectors 32, and springs 33 return the shafts 181, 191 to their normal position to bring the craft to level flight ; also, a switch 25 transfers the rudder control to a rate-of-turn gyroscope 27 having an inductive pick-off 28 whereby turning of the craft is prevented. If the aircraft is stalling when the master control button 24 is depressed, an angle-of-attack vane 35 moves over a resistance 37 to unbalance a Wheatstone bridge 80, whereby a magnet 38 shorts out the signal from the attitude gyro 13 controlling the elevator E and the unbalance e.m.f. operates the elevator motor 20 causing the aircraft to dive until it regains speed ; also, preferably a magnet' 39 opens the circuit controlling the ailerons A. Should the craft be upside down or in a bank of more than 90 degrees a semicircular contactor 40 on the axis 11 of the attitude gyro 13 breaks the circuit to the elevator motor 20 until the ailerons have unbanked the craft. In Fig. 2 (not shown), the angle-of-attack vane 35 is replaced by an air-speed meter and the contacter 40 by an independently mounted pendulum co-operating with a hemispherical bowl. Fig. 3 shows a modification in which pressing the control button 24 operates a switch 25 to prevent sideslip by transferring the rudder control to a sideslip detector vane 45 having a pick-up 46 ; also, a switch 47 is operated to prevent turning (and therefore banking) by transferring the aileron control to a rate-of-turn gyro 27<SP>1</SP>. Alternatively the ailerons may remain controlled by the attitude gyro which will maintain zero-bank and hence zero turn since there is no side slip. The system is suitable for tailless aircraft in which the control surfaces A would be controlled by a combination of signals from the directional gyro 2 and the gyro vertical 12. For automatic recovery from an abnormal condition, the rate-of-turn gyro 27<SP>1</SP> would be switched to control the surfaces A in place of the gyro 2. The Specification as open to inspection under Sect. 91 refers to Specification 659,791, [Group XXIX]. This reference does not appear in the Specification as accepted.